Methods and devices for inductive coupling into power lines

ABSTRACT

An electronic device is provided, including a housing having a back surface. The device includes a rechargeable battery, a capacitor, an inductor coil connected to the capacitor, the inductor coil being disposed around an axis oriented perpendicular to the back surface, a rectifier circuit connected to the inductor coil to output a direct current (DC), a DC-DC converter connected to the rectifier circuit, configured to trickle charge the battery with current received from the rectifier circuit, a test load switchably connected to the DC-DC converter, and a feedback circuit configured to detect a voltage level of the test load and provide an indication of the voltage level.

BACKGROUND

Electronic devices in a premises that monitor safety, security, climatecontrol, etc., are often mounted on walls in the premises and requirepower. Users typically prefer not to run wires to the devices fromoutlets for power. However, if batteries are used to power the devices,the user must periodically change the batteries. In some circumstances adevice may be nonfunctional during a critical time due to lack of powerfrom a dead battery that has not yet been changed. If, instead ofbatteries, a custom power delivery system is used involving splicingwires behind walls to power the devices, then professional installationis often required, which can be expensive for the user.

BRIEF SUMMARY

According to an embodiment of the disclosed subject matter, anelectronic device including a housing having a back surface, includes arechargeable battery, a capacitor, an inductor coil connected to thecapacitor, the inductor coil being disposed around an axis orientedperpendicular to the back surface, a rectifier circuit connected to theinductor coil to output a direct current (DC), a DC-DC converterconnected to the rectifier circuit, configured to trickle charge thebattery with current received from the rectifier circuit, a test loadswitchably connected to the DC-DC converter, and a feedback circuitconfigured to detect a voltage level of the test load and provide anindication of the voltage level.

According to another embodiment of the disclosed subject matter, amethod of inductive charging an electronic device using powerlinesdisposed in a premises, includes detecting, with the electronic device,a magnetic field generated by current in a powerline within a wall ofthe premises at a first location, determining a power generation levelthat the electronic device can achieve from inductive charging at thefirst location, moving the electronic device to a second location,providing, while the electronic device is moving, feedback indicating alevel of power generation achievable via induction from the powerline,attaching the electronic device to the wall at a position on the wallwhere the indicated level of power generation is above a thresholdvalue, and trickle-charging a rechargeable battery in the device usingan inductive charging power circuit disposed in the electronic device.

According to an embodiment of the disclosed subject matter, means forinductive charging an electronic device using powerlines disposed in apremises, including detecting, with the electronic device, a magneticfield generated by current in a powerline within a wall of the premisesat a first location, determining a power generation level that theelectronic device can achieve from inductive charging at the firstlocation, moving the electronic device to a second location, providing,while the electronic device is moving, feedback indicating a level ofpower generation achievable via induction from the powerline, attachingthe electronic device to the wall at a position on the wall where theindicated level of power generation is above a threshold value, andtrickle-charging a rechargeable battery in the device using an inductivecharging power circuit disposed in the electronic device are provided.

Additional features, advantages, and embodiments of the disclosedsubject matter may be set forth or apparent from consideration of thefollowing detailed description, drawings, and claims. Moreover, it is tobe understood that both the foregoing summary and the following detaileddescription are illustrative and are intended to provide furtherexplanation without limiting the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosed subject matter, are incorporated in andconstitute a part of this specification. The drawings also illustrateembodiments of the disclosed subject matter and together with thedetailed description serve to explain the principles of embodiments ofthe disclosed subject matter. No attempt is made to show structuraldetails in more detail than may be necessary for a fundamentalunderstanding of the disclosed subject matter and various ways in whichit may be practiced.

FIG. 1 shows an electronic device mounted on a wall according to anembodiment of the disclosed subject matter.

FIG. 2 shows an interior view of an electronic device according to anembodiment of the disclosed subject matter.

FIG. 3 shows a power circuit according to an embodiment of the disclosedsubject matter.

FIG. 4 shows an inductor configuration in electronic device according toan embodiment of the disclosed subject matter.

FIG. 5 shows another inductor configuration in electronic deviceaccording to an embodiment of the disclosed subject matter.

FIG. 6 shows an operational circuit in an electronic device according toan embodiment of the disclosed subject matter.

FIG. 7 shows a network configuration according to an embodiment of thedisclosed subject matter.

FIG. 8 shows a flowchart of an installation process according to anembodiment of the disclosed subject matter.

DETAILED DESCRIPTION

Various aspects or features of this disclosure are described withreference to the drawings, wherein like reference numerals are used torefer to like elements throughout. In this specification, numerousdetails are set forth in order to provide a thorough understanding ofthis disclosure. It should be understood, however, that certain aspectsof disclosed subject matter can be practiced without these specificdetails, or with other methods, components, materials, etc. In otherinstances, well-known structures and devices are shown in block diagramform to facilitate describing the subject disclosure.

Electrical power distribution systems commonly used in the United Statesand other countries distribute electrical power from a source tooutlets, lights, etc., in a premises via alternating current (AC) at 60Hz over cables attached to studs and/or beams disposed behind walls. Theembodiments disclosed herein include electronic devices configured todraw power from the cables using inductive charging techniques andconfigured to aid the user in an installation process so thatprofessional assistance is not required.

FIG. 1 shows an example use case for a disclosed embodiment that hasbeen installed in a premises. An electronic device 100 (in this example,a thermostat) is mounted on a wall 110. Behind the wall 110, a powerline120 connects a switch 130 to a light 140. When the switch 130 is closed,an alternating current flows through the powerline 120, causing thelight 140 to turn on. The alternating current flow creates analternating electromagnetic field 150 around the powerline 120. Theelectronic device 100 is mounted on the wall 110 in a position thatallows the device 100 to generate power from the alternatingelectromagnetic field 150.

A typical incandescent lightbulb draws approximately 50 W, and a singlelight switch normally supplies two or more lightbulbs, so the lightswitch power line will conservatively carry 100 W or more of power. Fora low power electronic device that draws approximately 100 μW onaverage, an coupling efficiency of 10⁻⁶ can be sufficient to power thedevice indefinitely. A low coupling efficiency requirement allows thecoil to be highly suboptimal, allowing for the use of smaller coils andcoil inductances/matching capacitances. A low coupling efficiencyrequirement also allows the use of different shaped coils, and allowslarger distances between the power source and the device than normallyallowed by wireless charging systems.

FIG. 2 shows an interior view of the electronic device 100, including afront surface 200, a back surface 210, an inductor coil 220, a powercircuit 230 and an operational circuit 240. The front surface 200 isshown removed in the direction of the straight arrows. The inductor coil220 is disposed on the back surface 210. When the device 100 is placedin close proximity to the alternating electromagnetic field 150surrounding the powerline 120, the inductor coil 220 generates analternating current that is captured by the power circuit 230 andtransmitted to the operational circuit 240. The operational circuit 240can be configured to handle any of various tasks, as will be describedfurther below.

The power circuit 230 will now be further described. FIG. 3 shows adiagram of an embodiment of a power circuit 230 according to thedisclosed subject matter. The configuration shown includes a capacitor310, an inductor coil 320, a rectifier circuit 330, a converter circuit340, a rechargeable battery 350, a test load 360, a switch mechanism370, and a feedback circuit 380. It should be understood that theconfiguration of the power circuit 230 can be modified, and othercomponents may be included that are not illustrated.

In one embodiment the inductor coil 320 comprises a four-inch coil withsixty turns, however, other configurations of coils can be used. Thecapacitor 310 is selected to tune the inductor coil 320 to apredetermined resonant frequency. In one embodiment, the capacitor 310is selected to achieve a resonant frequency of, or close to, 60 Hz,which is a standard AC frequency for powerlines in many locations. Inone embodiment, the coil 320 can be configured to achieve an inductanceof around 700 mH, and the capacitor can be selected to have acapacitance of around 10 mF. In this embodiment, the circuit can have aQ of around 100. Generally, configuring the circuit to have a high Qincreases the amount of power that can be generated.

The rectifier circuit 330 rectifies the current generated by theinductor coil 320 and the converter circuit 340 and trickle-charges thebattery 350 by converting the current to an appropriate voltage forcharging the battery 350. The battery 350 provides power to theoperational circuitry of the device.

The switch 370 can be switched from a first position that connects theconverter 340 to the battery 350, to a second position that disconnectsthe converter 340 from the battery 350 and connects the converter 340 toa test load 360. The feedback circuit 380 detects the voltage across thetest load 360 and provides an indication of the voltage level to theuser, as will be discussed further below.

The size, shape, and orientation of the coil can be altered in differentimplementations. Furthermore, the number of coils can also be altered.FIG. 4 shows an in inductor coil configuration in an embodiment of anelectronic device 400, including a front surface 450, a back surface410, a power circuit 430 and an operational circuit 440. Elements thathave already been previously described will not be further discussedhere. In this embodiment, the inductor coil 420 is oriented around anaxis that is parallel to the back surface 410. Depending on the size ofthe device and the components required for the operational circuit, thisconfiguration can provide a different option for the interiorpositioning of elements.

FIG. 5 shows another inductor coil configuration in an embodiment of anelectronic device 500 including a front surface 550, a back surface 510,a power circuit 530, and an operational circuit 540. This embodimentincludes a plurality of inductor coils 520.

As described above, the operational circuit executes functional tasksthat the device is designed to handle. For example, in one embodimentthe operational circuit can include a keypad input unit configured toreceive input from a user and a network interface unit configured totransmit a security signal to an external computing device based on acode entered in the keypad input unit. Both the keypad input unit andthe network interface unit can be powered by the battery in the powercircuit. In this embodiment the device can function as a security keypadentry unit.

In another embodiment, the operational circuit can include one or moretemperature sensors to measure ambient temperature, a user interfaceunit configured to receive input to control a heating, ventilation andair conditioning (HVAC) system, a network interface unit configured totransmit a control signal encoding a system command to control the HVACsystem based on the received input, and a display unit configured todisplay information related to the HVAC system. The one or moretemperature sensors, interface unit and display unit can be powered by abattery in the power circuit, where the battery is rechargeable usingthe apparatuses and methods described herein. In this embodiment thedevice can function as a thermostat.

In another embodiment, the operational circuit can include an imagesensing array configured to capture digital images, a processorconfigured to drive the image sensing array, and a memory configured tostore images captured by the image sensing array. The image sensingarray, the processor and the memory can be powered by the battery in thepower circuit, where the battery is rechargeable using the apparatusesand methods described herein.

FIG. 6 shows a general example embodiment of an operational circuit 20.The operational circuit 20 can include a bus 21 which interconnectscomponents, such as a central processor 24; a memory 27 such as RandomAccess Memory (RAM), Read Only Memory (ROM), flash RAM, or the like; auser display 22 such as a display screen or one or more light emittingdiodes (LEDs); a user input interface 26, which may include one or morecontrollers and associated user input devices such as a keyboard, mouse,touch screen, and the like; and a network interface 29 operable tocommunicate with one or more external devices via a suitable networkconnection. The circuit 20 may also include one or more sensors 28, afixed storage 23 such as a hard drive, flash storage, or the like,and/or a removable media component 25 operative to control and receive amemory card, optical disk, flash drive, or the like.

The bus 21 allows data communication between the central processor 24and one or more memory components, which may include RAM, ROM, and othermemory, as previously noted. Typically RAM is the main memory into whichan operating system and application programs are loaded. A ROM or flashmemory component can contain, among other code, the Basic Input-Outputsystem (BIOS) which controls basic hardware operation such as theinteraction with peripheral components.

The fixed storage 23 may be integral with the device or may be separateand accessed through other interfaces. The network interface 29 canprovide a direct connection to a remote server, system or other devicevia a wired or wireless connection. The network interface 29 may providesuch connection using any suitable technique and protocol as will bereadily understood by one of skill in the art, including digitalcellular telephone, WiFi, Bluetooth®, Thread®, near-field communication,and the like. For example, the network interface 29 may allow the deviceto communicate with other devices or computers via one or more local,wide-area, or other communication networks, as described in furtherdetail below.

The sensor 28 can be implemented as, for example, a digital imager,pixel array, temperature sensor, microphone, passive infrared detector,or other type of sensor that captures data that indicates informationabout an environment that the device is in.

Other devices or components (not shown) may be connected to theoperational circuitry in a similar manner, depending on thefunctionality of the device. Conversely, all of the components shown inFIG. 6 need not be present to practice the present disclosure. Thecomponents can be interconnected in different ways from theconfiguration shown. The software aspect of operation of a device suchas that shown in FIG. 6 is not discussed in detail in this application.Code to implement various features of the present disclosure can bestored in computer-readable storage media such as one or more of thememory 27, fixed storage 23, removable media 25, or on a remote storagelocation and accessible via the network interface 29.

FIG. 7 shows an example network arrangement according to an embodimentof the disclosed subject matter. One or more disclosed devices 10, 11,such as security keypads, smart thermostats, security sensors, or thelike may connect to other devices via one or more networks 7. Eachdevice may be a device including a power circuit inductively coupled toa powerline in a wall of a premises as previously described. The networkmay be a local network, wide-area network, the Internet, or any othersuitable communication network or networks, and may be implemented onany suitable platform including wired and/or wireless networks. Thedevices may communicate with one or more remote devices, such as servers13 and/or databases 15. The remote devices may be directly accessible bythe devices 10, 11, or one or more other devices may provideintermediary access such as where a server 13 provides access toresources stored in a database 15. The devices 10, 11 also may accessremote platforms 17 or services provided by remote platforms 17 such ascloud computing arrangements and services. The remote platform 17 mayinclude one or more servers 13 and/or databases 15.

Since the precise location of powerlines within a wall may be unknown tothe user, the disclosed electronic device can include a locator featureto aid a user in finding a location to install the device. FIG. 8 showsa process 800 of a feedback locator feature that the disclosed devicecan implement.

At operation 810 the user places the device against or near the wall. Atoperation 820 the device is switched to test mode in which the converteris disconnected from the battery and switched to be connected to a testload (see FIG. 3). The switch to test mode can occur manually, forexample, via the user manually moving a switch or pressing a button, orautomatically, for example by the device including a mechanical switchthat is configured to switch from a first position to a second lockedposition when a back surface of the device is pressed against a wall andremain locked until released to return to the first position.

In operation 830, while the device is in test mode the user moves thedevice along the wall. The user can be instructed, for example, to placethe device on the wall near a light switch, as shown in FIG. 1, turn thelight switch on to ensure that current is flowing in the powerline, andslide the device back and forth. While the device is moving the inductorwill move through an alternating electromagnetic field created by thecurrent in the powerline. The feedback circuit provides an indication ofthe amount of power that the power circuit is generating at eachlocation.

The feedback circuit can be implemented in various configurations toprovide the power indication. For example, in one embodiment thefeedback circuit can include a plurality of light emitting diodes (LEDs)in varying colors that are configured to illuminate at increasing powerlevel thresholds. For example, a red LED illuminates at a low powerlevel, a yellow LED illuminates at a higher power level, and a green LEDilluminates at a power level above a predetermined threshold that issufficient to charge the battery and power the device.

In another embodiment, the feedback circuit can include a transmitterconfigured to transmit an encoded signal to an external device, such asa cell phone or a computer. The signal can be encoded to indicate thedetected power level. The external device can be configured to decodethe signal and display a value or provide an audible indication of thevalue.

In another embodiment, the feedback circuit can include a speaker thatis configured to give an audible indication of the power level. Forexample, the speaker can be configured to beep at an increasingfrequency as the power level increases and at a decreasing frequency asthe power level decreases.

At operation 840 the user mounts the device on the wall based on thepower level indication provided by the feedback unit.

Accordingly, the disclosed device can be powered or recharged byinductive coupling, reducing the need for frequent battery changes andeliminating the need for professional installation.

In situations in which the systems discussed here collect personalinformation about users, or may make use of personal information, theusers may be provided with an opportunity to control whether programs orfeatures collect user information (e.g., information about a user'ssocial network, social actions or activities, profession, a user'spreferences, or a user's current location), or to control whether and/orhow to receive content from the content server that may be more relevantto the user. In addition, certain data may be treated in one or moreways before it is stored or used, so that personally identifiableinformation is removed. For example, a user's identity may be treated sothat no personally identifiable information can be determined for theuser, or a user's geographic location may be generalized where locationinformation is obtained (such as to a city, ZIP code, or state level),so that a particular location of a user cannot be determined. Thus, theuser may have control over how information is collected about the userand used by a system as disclosed herein.

More generally, various embodiments of the presently disclosed subjectmatter may include or be embodied in the form of computer-implementedprocesses and apparatuses for practicing those processes. Embodimentsalso may be embodied in the form of a computer program product havingcomputer program code containing instructions embodied in non-transitoryand/or tangible media, such as flash drives, CD-ROMs, hard drives, USB(universal serial bus) drives, or any other machine readable storagemedium, such that when the computer program code is loaded into andexecuted by a computing/smart device, the computing/smart device becomesan apparatus for implementing embodiments of the disclosed subjectmatter. Embodiments also may be embodied in the form of computer programcode, for example, whether stored in a storage medium, loaded intoand/or executed by a computing/smart device, or transmitted over sometransmission medium, such as over electrical wiring or cabling, throughfiber optics, or via electromagnetic radiation, such that when thecomputer program code is loaded into and executed by a computing/smartdevice, the computing/smart becomes an apparatus for practicingembodiments of the disclosed subject matter. When implemented on ageneral-purpose microprocessor, the computer program code segmentsconfigure the microprocessor to create specific logic circuits.

In some configurations, a set of computer-readable instructions storedon a computer-readable storage medium may be implemented by ageneral-purpose processor, which may transform the general-purposeprocessor or a device containing the general-purpose processor into aspecial-purpose device configured to implement or carry out theinstructions. Embodiments may be implemented using hardware that mayinclude a processor, such as a general purpose microprocessor and/or anApplication Specific Integrated Circuit (ASIC) that embodies all or partof the techniques according to embodiments of the disclosed subjectmatter in hardware and/or firmware. The processor may be coupled tomemory, such as RAM, ROM, flash memory, a hard disk or any other devicecapable of storing electronic information. The memory may storeinstructions adapted to be executed by the processor to perform thetechniques according to embodiments of the disclosed subject matter.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit embodiments of the disclosed subject matter to the precise formsdisclosed. Many modifications and variations are possible in view of theabove teachings. The embodiments were chosen and described in order toexplain the principles of embodiments of the disclosed subject matterand their practical applications, to thereby enable others skilled inthe art to utilize those embodiments as well as various embodiments withvarious modifications as may be suited to the particular usecontemplated.

1. An electronic device including a housing having a back surface,comprising: a rechargeable battery; a capacitor; an inductor coilconnected to the capacitor, the inductor coil being disposed around anaxis oriented perpendicular to the back surface; a rectifier circuitconnected to the inductor coil to output a direct current (DC); a DC-DCconverter connected to the rectifier circuit, configured to tricklecharge the battery with current received from the rectifier circuit; atest load switchably connected to the DC-DC converter; and a feedbackcircuit configured to detect a voltage level of the test load andprovide an indication of the voltage level.
 2. The device of claim 1,wherein the inductor coil is integrated in the back surface.
 3. Thedevice of claim 1, wherein the capacitor is selected to tune theinductor coil to a resonant frequency of approximately 60 Hz.
 4. Thedevice of claim 1, further comprising: a switch connected between thebattery and the DC-DC converter, such that when the switch is moved to afirst position the DC-DC converter is connected to the battery and whenthe switch is moved to a second position the DC-DC converter isdisconnected from the battery and is connected to the test load.
 5. Thedevice of claim 1, further comprising: a keypad input unit configured toreceive input from a user; a network interface unit configured totransmit a security signal to an external computing device based on acode entered in the keypad input unit, wherein the keypad input unit andthe network interface unit are powered by the battery.
 6. The device ofclaim 1, further comprising: a plurality of light emitting diodesdisposed on the housing, wherein the feedback circuit is configured toilluminate the plurality of light emitting diodes in varying colorsbased on the detected voltage level.
 7. The device of claim 1, whereinthe feedback circuit is configured to transmit an encoded signal to anexternal device, the encoded signal indicating the detected voltagelevel.
 8. The device of claim 1, further comprising: one or moretemperature sensors positioned within the housing for measuring ambienttemperature; a user interface unit configured to receive input tocontrol a heating, ventilation and air conditioning (HVAC) system; anetwork interface unit configured to transmit a control signal encodinga system command to control the HVAC system based on the received input;and a display unit configured to display information related to the HVACsystem, wherein the one or more temperature sensors, interface unit anddisplay unit are powered by the battery.
 9. The device of claim 1,further comprising: an image sensing array configured to capture digitalimages; a processor configured to drive the image sensing array; and amemory configured to store images captured by the image sensing array,wherein the image sensing array, the processor and the memory arepowered by the battery.
 10. The device of claim 1, further comprising: asensing circuit including an infrared sensor; and a lens disposed tofocus infrared energy onto the sensor, wherein the sensing circuit ispowered by the battery.